Photocrosslinkable polyester with side tricyclic imidyl groups

ABSTRACT

Photo-crosslinkable, novel polymers with side tricyclic imidyl groups, for example those of the formula ##STR1## are described. The novel photo-crosslinkable polymers are suitable for photo-mechanical applications, for example for the production of printing plates for the offset printing process and especially as photo-resists. They have high UV absorption and ensure a high rate of crosslinking even without the addition of photosensitizers.

This is a divisional of application Ser. No. 009,984, filed on Feb. 6,1979, now U.S. Pat. No. 4,283,509, issued on Aug. 11, 1981.

The present invention relates to novel photocrosslinkable polymers withside tricyclic imidyl groups, processes for their preparation and theiruse for photocrosslinking, especially to produce images.

It is known from the literature that diversely substituted imides, inparticular maleimides, are suitable for the preparation of crosslinkable(curable) polymers. Japanese Published Specifications 50-5376, 50-5377,50-5378, 50-5379 and 50-5380 describe generically differentα-arylmaleimides and N-substituted derivatives thereof which aresuitable for the preparation of photo-crosslinkable polymers; the saidderivatives can be further substituted in the β-position by a halogenatom, a cyano group or a lower alkyl group and the said alkyl group canalso form a ring together with the C atom in the ortho-position of theα-aryl group. The specific disclosure is restricted, however, toα-phenylmaleimides and α-phenyl-β-cyano-maleimides and N-substitutedderivatives thereof. In Japanese Published Specifications 49-128,991,49-128,992, 49-128,993, 50-9682, 50-10,884 and 50-77,363 the preparationof photo-crosslinkable polymers is described, for example by reactingN-substituted α-arylmaleimides of the abovementioned type, which havehydroxyl, amino, carboxylic acid or carboxylic acid chloride groups onthe N-substituent, with polymers containing corresponding functionalgroups. Further imidyl derivatives and photo-crosslinkable polymerscontaining imidyl groups in end or side positions, especially maleimide,dimthylmaleimide, nadicimide and tetrahydrophthalimide groups, are knownfrom German Offenlegungsschriften 2,031,573, 2,032,037 and 2,626,795.

These previously known imides and the crosslinkable polymers which canbe prepared therefrom have the disadvantage of a relatively lowphotochemical sensitivity and for this reason they are not suitable, ornot very suitable, for numerous applications for which highlyphotosensitive substances are required, or they require the additionaluse of known photosensitisers, such as benzophenone, thioxanthone andthe like.

The object of the invention was, therefore, to provide novelphoto-crosslinkable polymers which have a high UV absorption and,because of this, also ensure a high rate of crosslinking even withoutthe addition of photosensitisers.

The invention relates to novel photo-crosslinkable polymers which havean average molecular weight of at least 1,000 and have side imidylgroups of the formula I ##STR2## in which A is --CH₂ --, --CH₂ CH₂ -- or--OCH₂ -- with the oxygen atom bonded to the aromatic ring and E ishydrogen, or A is --O-- and E is --CH₃, and R and R₁ independently ofone another are hydrogen, halogen, alkyl having 1-4 C atoms or methoxy,the proportion of imidyl groups of the formula I being at least 5percent, preferably 5-100 and in particular 20-100 percent, based on thenumber of recurring structural elements in the polymer.

The polymers according to the invention advantageously have an averagemolecular weight of at least 1,000 to 1,000,000 and in particular anaverage molecular weight of about 1,000 to 200,000.

The polymers according to the invention are, for example, polyesters,polyester-amides, polyamides, polyimides, polyamide-imides,polyester-amide-imides, polyethers, polyamines, polyimines,polyurethanes, polycondensation products based on phenol-formaldehyde,polysaccharides, gelatin, organopolysiloxanes and polymers which areobtained by homopolymerisation or copolymerisation of monomerscontaining C═C double bonds.

The polymers according to the invention can be prepared by synthesismethods known per se for the preparation of macromolecules withphotoactive side groups. In principle, the following routes can be used:

1. Incorporation of the tricyclic imidyl groups of the formula I into anexisting polymer chain; and

2. Build-up of the polymer chain from monomers which already contain thephotosensitive tricyclic imidyl group, in which case the polymer chaincan be built up by polymerisation, polyaddition or polycondensation.

In some cases, the same products can be obtained with methods 1 and 2,so that method 1 or method 2 can be used as desired. If the tricyclicimidyl groups are incorporated into an existing polymer chain, thisincorporation is effected either by a condensation reaction or by anaddition reaction with simultaneous opening of a ring system, forexample of a dicarboxylic acid anhydride group or of an epoxide group.

According to the abovementioned build-up method, polymers according tothe invention can be prepared by polymerizing a compound of the formulaII

    imidyl--Y).sub.n-1 X                                       (II)

in which "imidyl" is a radical of the formula I, n is the number 1 or 2and Y is alkylene having 1-30 C atoms, which can be interrupted byhetero-atoms, or is cycloalkylene having 5 or 6 C atoms, adicyclohexylmethane radical, arylene having 6-10 C atoms, or aralkyleneor alkylarylene having 7 or 8 C atoms, it being possible for the saidradicals Y also to be substituted, and X, when n=1, is a group of theformulae --NH--CO-alkenyl or ##STR3## and, when n=2, is --CO--O-alkenyl,--O-alkenyl, --O--CO-alkenyl, --NH--CO-alkenyl or --S--CO-alkenyl, the--COR₂ s are bonded to the benzene ring in the meta- or para-positionrelative to one another and the R₂ s are each --OH, --Cl, alkoxy having1-4 C atoms or phenoxy, or the --COR₂ s are bonded to the benzene ringin the ortho-position relative to one another and one of the R₂ s is--OH or --O⁻ M⁺ and the other is ##STR4## or the two R₂ s together are--O--, and M⁺ is an alkali metal cation, the pyridinium cation or atrialkylammonium cation having 3-24 and especially 3-12 C atoms, Q₁ ishydrogen or methyl and q is an integer from 2 to 4, and, in the abovegroups, alkenyl moieties have 2-4 C atoms, if desired in the presence ofcomonomers, the molar ratio of the compound of the formula II to thecomonomer being 1:20 to 1:10 and preferably 1:4 to 1:0.

According to the abovementioned incorporation method, polymers accordingto the invention can be prepared, for example, by reacting a compound ofthe formula III

    imidyl--Y).sub.n-1 X'                                      (III)

in which "imidyl" is a radical of the formula I, n and Y are as definedunder formula I and X', when n=1, is a group of the formula ##STR5##and, when n=2, is --OH, --NH₂, --NH-alkyl having 1-4 C atoms, --SH,--COOH or --COCl, with a polymer containing corresponding functionalgroups in a ratio of 1:20 to 1:1 and preferably 1:5 to 1:1, based on thenumber of recurring structural elements in the polymer.

Compounds of the formula III in which X' is --COOH, --COCl or a phthalicanhydride group can, for example, be reacted with polymers which containfree --OH, --NH₂, --NH-alkyl or --SH groups. Compounds of the formulaIII in which n is the number 2 and X' is --OH, --NH₂, --NH-alkyl having1-4 C atoms or --SH are suitable, for example, for reaction withpolymers which contain --COOH or anhydride groups. Finally, compounds ofthe formula III in which n is the number 2 and X' is --OH, --NH₂,--NH-alkyl having 1-4 C atoms, --SH or --COOH can also be reacted withpolymers which contain ##STR6## groups.

Alkylene, cycloalkylene, dicyclohexylmethane, arylene, aralkylene oralkylarylene groups Y, according to the definition, can be unsubstitutedor substituted, for example by alkyl or alkoxy groups each having 1-4 Catoms and in particular each having 1 or 2 C atoms, nitro groups orhalogen atoms, such as chlorine, bromine or fluorine.

Alkylene groups Y can be straight-chain or branched and can contain oneor more hetero-atoms, especially S or O atoms. Unsubstituted,straight-chain or branched alkylene groups are preferred, especiallythose having 2-10 C atoms. Examples of suitable alkylene groups Y arethe ethylene group, the 1,3- or iso-propylene group, the2,2-dimethylpropylene group, the tetramethylene group, the hexamethylenegroup, the octamethylene group and the decamethylene group.

A cycloalkylene group Y is preferably unsubstituted. It is especiallythe 1,3-cyclohexylene group and in particular the 1,4-cyclohexylenegroup.

Substituted arylene groups Y preferably have only one substituent perring and this substituent is in particular an alkyl or alkoxy group,each having 1-4 and in particular 1 or 2 C atoms, or a nitro group.Examples of suitable arylene groups Y are the 1,2-, 1,3- and1,4-phenylene group, the 1,3-tolylene group, the 5-methoxy-1,3-phenylenegroup, the 3-nitro-1,4-phenylene group and the 1,7- or 2,7-naphthylenegroup. Unsubstituted arylene groups are preferred, especially the1,4-phenylene group and the 1,3-phenylene group.

Aralkylene groups Y are, in particular, the groups ##STR7## andalkylarylene groups Y are, in particular, the groups ##STR8##

Alkyl or alkoxy groups R, R₁, R₂ and R₂ ' according to the definition,and also alkyl or alkenyl moieties of substituents X or X' according tothe definition, can also be straight-chain or branched.

Examples of alkyl, alkoxy and alkenyl groups according to the definitionare: the methyl, ethyl, propyl, isopropyl, n-butyl, tert.-butyl,methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert.-butoxy, vinyl,allyl and isopropenyl group.

If the substituent X contains an alkenyl group, the latter are, inparticular, ##STR9## groups in which Q₁ is hydrogen or methyl.

A halogen atom R or R₁ is in particular a chlorine, bromine or fluorineatom. Alkyl groups R and R₁ are advantageously straight-chain and have 1or 2 C atoms. Preferably, however, R and R₁ are each hydrogen.

Alkoxy groups R₂ and R₂ ' are likewise preferably straight-chain andhave 1 or 2 C atoms.

M⁺ is, for example, the lithium, sodium, potassium, trimethylammonium,triethylammonium or methyldiethylammonium cation or thetri-n-octylammonium cation. Preferably, M⁺ is an alkali metal cation,especially the sodium cation.

Preferred groups ##STR10## are those in which the groups --COR₂ and--COR₂ ' are bonded to the benzene ring in the 3,5-position and the R₂ sand R₂ 's are each --OH, methoxy, ethoxy, phenoxy or chlorine, or thosein which the groups --COR₂ and --COR₂ ' are bonded to the benzene ringin the ortho-position relative to one another and the two R₂ s and R₂ 'stogether are --O--.

Preferred tricyclic imidyl groups of the formula I and compounds of theformula II or III are those in which R and R₁ are each hydrogen, A is--CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atom bonded to thearomatic ring, and E is hydrogen.

Compounds of the formula II in which X is a polymerisable group orcontains a polymerisable grouping are suitable for homopolymerisation orfor copolymerisation with other ethylenically unsaturated comonomers,especially those of the type indicated further below. Compounds of theformula II in which X is a group ##STR11## in which the --COR₂ s arebonded to the benzene ring in the meta- or para-position relative to oneanother and the R₂ s are each --OH, --Cl, alkoxy having 1-4 C atoms orphenoxy, or in which the --COR₂ s are bonded to the benzene ring in theo-position relative to one another and the R₂ s together form --O--, canbe subjected to a polycondensation reaction with suitable diamines,diols, aminoalcohols and, if desired, further di-, tri- ortetra-carboxylic acid derivatives. The co-condensation components whichcan be employed are, per se, any desired aliphatic, cycloaliphatic,araliphatic, carbocyclic-aromatic or heterocyclic compounds.

Examples of starting polymers which can be reacted with compounds of theformula III are: polyacrylic acid, polymethacrylic acid, copolymers ofthese acids and other ethylenically unsaturated monomers, copolymersbuilt up from maleic anhydride and ethylenically unsaturated monomers,such as methyl vinyl ether, ethylene, styrene, 1-hexene, 1-decene,1-tetracene and 1-octadecene, polymers with free hydroxyl groups, suchas homopolymers and copolymers of hydroxylalkyl acrylates andhydroxyalkyl methacrylates, polyvinyl alcohols, natural or regeneratedcellulose, cellulose derivatives, hydroxyalkylcellulose, polyethers withfree OH groups, phenolformaldehyde polycondensation products, polymerswith free glycidyl groups, such as copolymers based on glycidylacrylates and glycidyl methacrylates, polyethyleneimines and polymerswith free side amino groups, for example poly-p-aminostyrene.

Preferred polymers according to the invention are those which containrecurring structural elements of the formula IV to VII and X to XIV:##STR12##

In the above formulae "imidyl" is a radical of the formula I, R₂ ' is--OH or --O⁻ M⁺, Q₁ is hydrogen or methyl, q is an integer from 2 to 4,p is the number 1 or 2, Z is --O--, --NH--, --N-alkyl having 1-4 C atomsor --S--, Z₁ is --OCO--, --NH--, --N-alkyl having 1-4 C atoms, --O-- or--S-- and Z₂ is --O--, --S-- or --NH--.

Further preferred polymers according to the invention are those which,in addition to one or more of the structural elements of the formulae IVto VII and X to XIV, at the same time contain structural elements of theformula XVI ##STR13## in which X₁ and X₃ are each hydrogen, X₂ ishydrogen, chlorine or methyl and X₄ is hydrogen, methyl, chlorine, --CN,--COOH, --CONH₂, phenyl, methylphenyl, methoxyphenyl, cyclohexyl,pyridyl, imidazolyl, pyrrolidyl, --COO-alkyl having 1-12 C atoms in thealkyl moiety, --COO-phenyl, ##STR14## --COO-alkyl-OH having 1-3 C atomsin the alkyl moiety, --OCO-alkyl having 1-4 C atoms in the alkyl,--OCO-phenyl, --CO-alkyl having 1-3 C atoms in the alkyl, alkoxy having1-6 C atoms or phenoxy, or X₁ and X₂ are each hydrogen and X₃ and X₄together are the grouping ##STR15## or each are --COOH or --COO-alkylhaving 1-6 C atoms in the alkyl.

Copolymers of particular interest amongst those of the last-mentionedtype are those which contain structural elements of the formula XVI, inwhich X₁ and X₃ are each hydrogen, X₂ is hydrogen or methyl and X₄ is--OCOCH₃, --COOH or --COO-alkyl having 1-8 C atoms in the alkyl, or X₁,X₂ and X₃ are each hydrogen and X₄ is --CN, chlorine or phenyl.

Further preferred polymers according to the invention arehomopolycondensation products or copolycondensation products which haveaverage molecular weights of between 1,000 and 50,000 and which containthe maleimide groups of the formula I in molecule chain members of theformula XV ##STR16## in which Z₃ and Z₄ independently of one another are--O--, --NH-- or --S-- and G is an aliphatic radical having at least 2 Catoms or a cycloaliphatic, araliphatic, carbocyclicaromatic orheterocyclic-aromatic radical, or Z₃ -G-Z₄ - is a grouping of theformulae ##STR17## and R₃ and R₄ independently of one another arehydrogen, methyl or phenyl, the two carbonyl groups in the formula XVbeing bonded to the benzene ring in the meta- or para-position relativeto one another.

Further preferred polymers are those which, in addition to one or morestructural elements of the formula XV, at the same time containstructural elements of the formula XVII ##STR18## in which Z₃, Z₄ and Gare as defined under formula XV, m and r independently of one anotherare the number 1 or 2 and G₁ is an aliphatic radical having at least 2 Catoms or a cycloaliphatic, araliphatic, carbocyclic-aromatic orheterocyclic-aromatic radical and in which the carbonyl and carboxylgroups are bonded to different C atoms and, in the case of cyclicradicals G₁, are bonded in pairs to adjacent C atoms.

An aliphatic radical G is, in particular, straight-chain or branchedalkylene having 2-12 C atoms, it being possible for the alkylene chainalso to be interrupted by hetero-atoms, such as O, S or N atoms. Acycloaliphatic radical G is, for example, the 1,3- or 1,4-cyclohexylenegroup, the 1,4-bis-(methylene)-cyclohexane group or thedicyclohexylmethane group. Araliphatic radicals G are, in particular,1,3-, 1,4- or 2,4-bis-alkylenebenzene, 4,4'-bis-alkylenediphenyl and4,4'-bis-alkylenediphenyl ether groups, in particular the 1,3- and1,4-xylylene group and the 1,3-tolylene group. Carbocyclic-aromaticradicals G can be mononuclear or polynuclear and fused or non-fused andin the latter case the aromatic nuclei are bonded to one another via abridge member. In particular, such radicals are phenylene or naphthylenegroups which are unsubstituted or substituted by alkyl or alkoxy groupseach having 1-4 C atoms or by halogen atoms, such as chlorine, bromineor fluorine, or groups of the formula ##STR19## in which Q₂ is --O--,--CH₂ --, --S--, --SO₂ -- or --C(CH₃)₂ --. Heterocyclic-aromaticradicals G are, for example, five-membered or six-membered ring systemscontaining N, O and/or S.

An aliphatic radical G₁ is, for example, straight-chain or branchedalkylene having 2-12 C atoms, especially straight-chain alkylene having2-10 C atoms. Cycloaliphatic radicals G₁ are, in particular, 5-memberedor 6-membered cycloalkyl groups. A carbocyclic-aromatic radical G₁preferably contains at least one 6-membered ring; in particular suchradicals are monocyclic, fused bicyclic or non-fused bicyclic radicalsand the latter can also be bonded to one another via a bridge member,such as --CO-- or --CH₂ --. Heterocyclic-aromatic radicals G₁ areespecially 5-membered or 6-membered heterocyclic-aromatic ring systemswhich contain O, N and/or S and can be benzo-condensed.

When m and r=1, G₁ is preferably straight-chain alkylene having 2-10 Catoms or 1,3- or 1,4-phenylene. If one of m and r is the number 1 andthe other is the number 2, G₁ is, in particular, a benzenetriyl group.When m and r=2, G₁ is, in particular, a benzenetetrayl group or thebenzophenone ring system.

Copolycondensates of the last-mentioned type which are particularlyadvantageous industrially are those which contain recurring structuralelements of the formula XVa ##STR20## and can contain recurringstructural elements of the formula XVIIa ##STR21## in which formulae"imidyl" is a radical of the formula I in which R and R₁ are eachhydrogen, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atombonded to the aromatic ring and E is hydrogen, and Z₃ and Z₄ are each--NH-- or --O--, G is alkylene having 2-12 C atoms or arylene having6-10 C atoms, which can be substituted by halogen atoms or alkyl groupshaving 1-4 C atoms, and G₁ is alkylene having 2-10 C atoms or 1,3- or1,4-phenylene, or --Z₄ --G--Z₃ -- is the grouping ##STR22## in which R₃and R₄ are each hydrogen or methyl.

Polymers containing recurring structural elements of the formula XV canbe obtained by subjecting a compound of the formula II, in which n isthe number 1 and X is a group of the formula ##STR23## in which the--COR₂ s are bonded to the benzene ring in the meta- or para-positionrelative to one another and the R₂ s are each --OH, --Cl, alkoxy having1-4 C atoms or phenoxy, to a polycondensation reaction with a compoundof the formula XVIII

    HZ.sub.3 --G--Z.sub.4 H                                    (XVIII)

if desired in the presence of a di-, tri- or tetracarboxylic acidderivative, for example those of the formula XIX ##STR24## in whichformulae Z₃, Z₄, G, G₁, m and r are as defined above and M₁, when m andr=1, is --OH, --Cl, alkoxy having 1-4 C atoms or phenoxy and, when mand/or r=2, together with M₂ is --O--.

Finally, polymers which contain recurring structural elements of theformulae IV to VIII or XII can be prepared by

(A) reacting a compound of the formula III in which Y is as defined, nis the number 2 and X' is --COCl or --COOH with a polymer containingrecurring structural elements of the formulae IVa or Va ##STR25##

(B) reacting a compound of the formula III in which Y is as defined, nis the number 2 and X' is --OH, --NH₂, --NH-alkyl having 1-4 C atoms or--SH with a polymer containing recurring structural elements of theformula VIa ##STR26##

(C) reacting a compound of the formula III in which Y is as defined, nis the number 2 and X' is --OH, --NH₂, --NH-alkyl having 1-4 C atoms,--SH or --COOH with a polymer containing recurring structural elementsof the formulae VIIa or VIIIa ##STR27## or

(D) reacting a compound of the formula III in which n is the number 1and X' is a group ##STR28## with a polymer containing recurringstructural elements of the formula IVa, Q₁ and p in the above formulaebeing as defined above.

Particularly preferred polymers are those which contain recurringstructural elements of the formulae IV, V, VI, VII, VIII, X, XII or XIVand can contain recurring structural elements of the formula XVI and inwhich, in the imidyl radical of the formula I, R and R₁ are eachhydrogen, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atombonded to the aromatic ring and E is hydrogen, Y is straight-chain orbranched alkylene having 2-11 C atoms, 1,3- or 1,4-phenylene or1,4-cyclohexylene, Z is --O-- or --NH--, Z₁ is --OCO-- or --NH--, p isthe number 1 and Q₁ is methyl or in particular hydrogen and X₁, X₂, X₃and X₄ have the preferred meaning defined above.

A particularly preferred type of polymers according to the inventioncomprises those which are based on novolacs as the starting material andwhich contain recurring structural elements of the formula VIII##STR29## in which p, Z₁, Y and imidyl are as defined for formula VII.

Finally, further preferred polymers are those which contain recurringstructural elements of the formulae IV, V, VI, VII, VIII, X, XII or XIVand can contain recurring structural elements of the formula XVI and inwhich, in the imidyl radical of the formula I, R and R₁ are eachhydrogen, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atombonded to the aromatic ring and E is hydrogen, Y is straight-chain orbranched alkylene having 2-11 C atoms, 1,3- or 1,4-phenylene or1,4-cyclohexylene, Z is --O-- or --NH--, Z₁ is --OCO-- or --NH--, p isthe number 1, Q₁ is methyl or in particular hydrogen and X₁ and X₃ areeach hydrogen, X₂ is hydrogen or methyl and X₄ is --OCOCH₃, --COOH or--COO-alkyl having 1-8 C atoms in the alkyl, or X₁, X₂ and X₃ are eachhydrogen and X₄ is --CN, chlorine or phenyl.

The incorporation of tricyclic imidyl groups according to the inventioninto existing polymer chains by means of a condensation or additionreaction and also the build-up of polymers according to the invention,for example those containing structural elements of the formula XV, bypolycondensation of suitable monomers can be carried out in a mannerknown per se, advantageously at temperatures of about -50° C. to +150°C. The reaction is preferably carried out in an inert organic solvent ora solvent mixture and in the case of condensation reactions ispreferably carried out at temperatures of about -20° C. to +100° C.Addition reactions are advantageously carried out at elevatedtemperature, in general at temperatures between about 80° and 120° C. orat the reflux temperature.

Suitable solvents for carrying out the condensation or additionreactions are, for example: aliphatic or cyclic ketones, such asacetone, methyl ethyl ketone, isopropyl methyl ketone, cyclohexanone,cyclopentanone and γ-butyrolactone; cyclic ethers, such astetrahydrofuran, tetrahydropyran and dioxan; cyclic amides, such asN-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone andN-methyl-ε-caprolactam; N,N-dialkylamides of aliphatic monocarboxylicacids having 1-3 C atoms in the acid moiety, such asN,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide andN,N-dimethylmethoxyacetamide; pyridine and pyridine bases or tertiaryamines, in particular trialkylamines and dialkylbenzylamines having,preferably 1-4 C atoms in the alkyl moieties, for example triethylamineand diethylbenzylamine; and dialkylsulphoxides, such asdimethylsulphoxide and diethylsulphoxide.

Preferred solvents for condensation reactions are cyclic amides andN,N-dialkylamides of the abovementioned type, especiallyN-methyl-2-pyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide.For addition reactions, cyclic ethers and cyclic ketones, in particulartetrahydrofuran and cyclohexanone, and also pyridine are preferred.

Catalysts which promote the desired linking can also be added to thereaction solution. Thus, for example, the addition of tertiary amines,such as triethylamine or pyridine, quaternary ammonium salts, such astetraalkylammonium chlorides having, in each case, 1-4 and preferably 1or 2 C atoms in the alkyl groups, p-toluenesulphonic acid orconcentrated sulphuric acid is advantageous for the formation of esters.

After the reaction, the polymers modified by the tricyclic imidyl groupsaccording to the definition can be precipitated by the addition of aslightly polar solvent. Examples of such slightly polar solvents aredialkyl ethers having, in each case, 2-4 C atoms in the alkyl moieties,such as diethyl ether and di-n-propyl ether, alcohols having up to 6 Catoms, such as methanol, ethanol, isopropanol, butanols and pentanols,and aliphatic, cycloaliphatic or aromatic hydrocarbons, such asn-pentane, n-hexane, cyclohexane, benzene and toluene.

The homopolymerisation of compounds of the formula II in which X is apolymerisable group or contains a polymerisable grouping, and also thecopolymerisation of these compounds with other ethylenically unsaturatedmonomers, for example those of the formula XVIa, can likewise be carriedout in a manner known per se, for example in the presence of customarycationic and anionic initiators. Free radical polymerisation ispreferred. In this case it is advantageous to use about 0.01 to 5% byweight and preferably 0.01 to 1.5% by weight, based on the total weightof monomers, of free radical initiators known per se, such as inorganicor organic peroxides or azo compounds, for example hydrogen peroxide,potassium peroxydisulphate, tert.-butyl hydroperoxide, di-tert.-butylperoxide, peracetic acid, benzoyl peroxide, diacyl peroxide, cumenehydroperoxide, tert.-butyl perbenzoate, tert.-alkyl peroxycarbonates andα,α'-azoisobutyronitrile. The reaction temperatures for the free radicalpolymerisation are generally between about 30° and 100° C. The freeradical polymerisation can, however, also be carried out in the coldand, for this purpose, it is also possible to use redox systems in theabovementioned concentrations, for example mixtures of peroxides, suchas hydrogen peroxide, and a reducing agent, such as divalent iron ions.

The polymerisation can be carried out in homogeneous phase, for examplein bulk (block polymerisation) or in solution, or in heterogeneousphase, i.e. as precipitation polymerisation, emulsion polymerisation orsuspension polymerisation. Polymerisation in solution is preferred.

Suitable solvents are those of the type mentioned for the condensationand addition reactions and also: halogenated aromatic hydrocarbons, suchas chlorobenzene and dichlorobenzenes; chlorinated aliphatichydrocarbons, such as methylene chloride, chloroform, tetrachloroethaneand tetrachloroethylene; alkyl esters of aliphatic monocarboxylic acidshaving a total of 2-6 C atoms, such as methyl formate, ethyl formate andn-butyl formate or methyl acetate, ethyl acetate and n-butyl acetate;and ethylene glycol dialkyl ethers having 1-4 C atoms in the alkylmoieties, such as ethylene glycol dimethyl ether, ethylene glycoldiethyl ether and ethylene glycol di-n-butyl ether.

Mixtures of such solvents can also be used.

After the reaction has ended, the polymer can be precipitated by pouringthe reaction mixture into suitable organic solvents, for examplealiphatic hydrocarbons, alcohols or dialkyl ethers, such as n-pentane,n-hexane, methanol, ethanol and diethyl ether.

The compounds of the formula II and III which are to be used for thepreparation of the polymers according to the invention and in which A is--CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atom bonded to thearomatic ring and E is hydrogen and Y, n, X and X' are as defined can beprepared by reacting a compound of the formula XX ##STR30## in which A'is --CH₂ --, --CH₂ CH₂ -- or --OCH₂ -- with the oxygen atom bonded tothe aromatic ring and R and R₁ are as defined under formula I, with acompound of the formula XXI

    H.sub.2 N--Y).sub.n-1 X"                                   (XXI)

in which Y and n are as defined under formula II and X", when n=1, is agroup of the formula ##STR31## and, when n=2, is --OH, --NH₂, --NH-alkylhaving 1-4 C atoms, --COOH, --SH or --O-alkenyl having 2-4 C atoms inthe alkenyl moiety, and the --COR₂ " groups are bonded to the benzenering in the meta- or para-position relative to one another and the R₂ "sare each --OH, --Cl, alkoxy having 1-4 C atoms or phenoxy, or the --COR₂" groups are bonded to the benzene ring in the ortho-position relativeto one another and the R₂ "s together form --O--, and M⁺ is as definedunder formula II, if necessary cyclising amidocarboxylic acids whichhave formed as intermediates and, if desired, subsequently convertingthe imide into a compound of the formula II or III in which X" differsfrom X and X'.

Compounds of the formula II and III in which A is --O-- and E is --CH₃and R, R₁, Y and n are as defined under formula I or II can be obtainedby rearranging a compound of the formula II or III in which A=--OCH₂ --into a compound of the formula II or III in which A=--O-- and E=--CH₃,by the action of heat or in the presence of a basic catalyst.

The compounds of the formula XXI and the compounds of the formula XX inwhich A' is --CH₂ -- are known or can be prepared according to methodsknown per se. Compounds of the formula XX in which A' is --CH₂ CH₂ -- or--OCH₂ -- can be prepared, for example, by reacting 5-phenylvaleric acidesters or phenoxybutyric acid esters, which can be ring-substituted,with an oxalic acid diester to give the 3-phenylpropyl- or2-phenoxyethyl-oxaloacetic acid diester and treating the reactionproduct with a strong acid, such as concentrated sulphuric acid.

The reaction of the amines of the formula XXI with the anhydrides of theformula XX can be carried out in the melt by heating the reactants totemperatures of up to about 250° C., or, alternatively, can be carriedout in an aqueous, aqueous-organic or organic medium. The organicsolvents are in particular aprotic organic solvents, for examplealiphatic or aromatic hydrocarbons, which can be halogenated, cyclicethers, cyclic amides, N,N-dialkylamides of aliphatic monocarboxylicacids or dialkylsulphoxides of the abovementioned type.

Amidocarboxylic acids which may have been formed as intermediates can becyclised to the imides in a manner known per se, chemically or by theaction of heat.

The conversion to compounds of the formula II or III in which X" differsfrom X and X' can likewise be carried out in a manner known per se, forexample:

X=--NH--CO-alkenyl (n=1 or 2): by reacting reaction products in whichn=1 or 2 and X"=--NH₂ with alkenyl-COCl.

X or X'=a phthalic anhydride radical or one R₂ in theortho-position=--OH and the other R₂ = ##STR32## by cyclisingcorresponding compounds in which X"=a phthalic acid radical and, ifnecessary, subsequently reacting the product with alcohols ##STR33##

X"=--COCl or R₂ =--Cl: by treating the free acids with a chlorinatingagent, such as thionyl chloride, oxalyl chloride or phosgene.

X=--CO--O-alkenyl: by reacting the corresponding free acids or the acidchlorides with unsaturated esters or alcohols in the presence of acidsor bases.

X=--O--CO-alkenyl or --S--CO-alkenyl: by reacting compounds of theformula III in which X'=--OH or --SH with corresponding unsaturatedacids, acid chlorides or esters.

The polymers according to the invention are photo-crosslinkable and aresuitable, for example, for the production of printing plates for theoffset printing process, for the production of photo-offset lacquers andfor unconventional photography, for example for staining polymer imageswhich are difficult to see after exposure and developing, staining beingcarried out with suitable dyes, such as oil-soluble dyes or, if thepolymer contains acid groups, such as carboxylic acid groups orsulphonic acid groups, cationic dyes. The polymers according to theinvention are used, in particular, as so-called photoresists for theproduction of printed circuits by methods known per se. In this case,the side of the conductor plate provided with the photo-sensitive layeris exposed through a transparency negative containing the conductorimage and then developed, after which the unexposed areas of the layerare removed by developer liquid. Exposure can be carried out withsunlight, carbon arc lamps or xenon lamps. Advantageously, exposure iscarried out with mercury high pressure lamps. The support materials canbe coated with the photosensitive polymers by techniques which arecustomary per se, for example by dipping processes, spray-coating,whirler coating, cascade-coating or curtain-coating or "roller-coating".

EXAMPLE 1

100 g of a copolymer of methyl vinyl ether and maleic anhydride (1:1;anhydride content=0.64 mol, average molecular weight 740,000), 77.8 g(0.32 mol) ofN-(2'-hydroxyethyl)-3,4-dihydronaphthalene-1,2-dicarboximide and 10 mlof pyridine are dissolved in 1,820 ml of dried tetrahydrofuran. Thereaction mixture is kept at 80° C. for 72 hours, with stirring. Aftercooling to room temperature (20°-25° C.), the clear solution isprecipitated in 5 liters of diethyl ether and the precipitate is driedin vacuo. This yields 141.0 g (79.3% of theory) of a white polymer. Forelementary analysis, a sample of the polymer is precipitated in 0.1 NHCl.

Elementary analysis: found: C 55.3%, H 5.9%, N 2.23%.

Further polymers are prepared in an analogous manner using thecomponents indicated in Table I below.

                                      TABLE I                                     __________________________________________________________________________    Example                                     g of                                                                              g of                          No.    Imide          Polymer               imide                                                                             polymer                       __________________________________________________________________________    2    N--(2'-hydroxyethyl)-6,7-dihydro- 5H-benzocycloheptene-8,9- dicarboxy         lic acid imide                                                                                  ##STR34##            82.3                                                                              100                           3    N--(2'-hydroxyethyl)-2-methyl-                                                                 "                     82.9                                                                              100                                2H-chromene-3,4-dicarboximide                                            4    N--(2'-hydroxyethyl)-2,3-dihydro-                                                              "                     78.4                                                                              100                                1-benzoxepine-4,5-dicarboximide                                          5    N--(3'-hydroxy-2',2'-dimethyl-                                                                 "                     87.4                                                                              100                                propyl)-3,4-dihydronaphthalene-                                               1,2-dicarboxylic acid imide                                              6    N--(3'-hydroxy-2',2'-dimethyl-                                                                 "                     95.6                                                                              100                                propyl)-6,7-dihydro-5H-benzo-                                                 cycloheptene-8,9-dicarboxylic                                                 acid imide                                                               __________________________________________________________________________

EXAMPLE 7 ##STR35##

4.1 g of polyvinyl alcohol with an average molecular weight of about13,000 and a residual acetate content of 12% are heated together with36.6 ml of anhydrous pyridine for 15 hours at 100° C. A further 36.6 mlof anhydrous pyridine are then added and the solution is cooled rapidlyto 50° C. 0.59 g of diazabicyclooctane, dissolved in 3.7 ml of anhydrouspyridine, are now added, directly thereafter 12.9 g (0.038 mol) ofN-(caproic acid chloride)-3,4-dihydronaphthalene-1,2-dicarboximide areadded in portions and the resulting mixture is stirred for 4 hours at50° C. After cooling to room temperature, 90 ml of acetone are added.The pyridinium hydrochloride which has precipitated out is filtered offand the filtrate is precipitated in 2 liters of water. After drying theproduct over P₂ O₅, 10 g (75.8% of theory) of a brownish polymer whichhas a viscosity, η inherent (25° C., DMF), of 0.3 are obtained.

EXAMPLE 8

31.1 g (0.1 mol) ofN-(2'-methacryloyloxyethyl)-3,4-dihydronaphthalene-1,2-dicarboxylic acidimide together with 0.31 g of α,α'-azoisobutyronitrile are dissolved in140 ml of tetrahydrofuran. The reaction mixture is polymerised under agentle reflux (about 80° C.) for 6 hours under nitrogen and withcontinuous stirring. After the reaction has ended, the reaction solutionis cooled to room temperature and the polymer is precipitated by addingthe reaction solution dropwise to 2 liters of hexane. This yields 24.4 g(78.5% of theory) of a white powder; inherent viscosity: 0.15 dl/g (0.5%by weight, measured at 20° C. in N,N-dimethylformamide).

EXAMPLES 9 TO 14

Further photo-sensitive polymers are prepared under reaction conditionsanalogous to those in Example 8; the preparation and viscosity inchloroform of these polymers are illustrated in Table II.

                                      TABLE II                                    __________________________________________________________________________    (analogous to Example 7 in the text)                                          Ex- Polymer composition                    η limiting                     ample                                                                              Monomer I     Mol %                                                                             Monomer II  Mol %                                                                             Yield                                                                             in CHCl.sub.3                      __________________________________________________________________________    9   N--(2-methacryloyloxyethyl)-                                                                 100 --          --  70% 0.075                                                                             dl/g*                              3,4-dihydronaphthalene-1,2-                                                   dicarboxylic acid imide                                                   10  N--(2-methacryloyloxyethyl)-                                                                 70  N--vinyl-2-pyrrolidone                                                                    30  16% 0.12                                                                              dl/g                               3,4-dihydronaphthalene-1,2-                                                   dicarboxylic acid imide                                                   11  N--(2-methacryloyloxyethyl)-                                                                 60  2-ethylhexyl acrylate                                                                     40  18% 0.2 dl/g                               3,4-dihydronaphthalene-1,2-                                                   dicarboxylic acid imide                                                   12  N--(2-methacryloyloxyethyl)-                                                                 50  methyl methacrylate                                                                       50  38% 0.18                                                                              dl/g                               3,4-dihydronaphthalene-1,2-                                                   dicarboxylic acid imide                                                   13  N--(2-methacryloyloxyethyl)-                                                                 60  4-vinylpyridine                                                                           40   9% 0.08                                                                              dl/g                               3,4-dihydronaphthalene-1,2-                                                   dicarboxylic acid imide                                                   14  N--(2-acryloyloxyethyl)-                                                                     100 --          --  40% 0.06                                                                              dl/g                               3,4'-dihydronaphthalene-                                                      1,2-dicarboxylic acid                                                         imide                                                                     __________________________________________________________________________     *Tg 126° C.                                                            --Mw 36,000                                                              

EXAMPLE 15

2.5 g (0.00662 mol) of N-(3-isophthaloyldicarboxylicacid)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid imide and1.75 g (0.00729 mol) of 1,3-diglycidyl-5,5-dimethylhydantoin aredissolved in 85 ml of cyclohexanone and 1 crystal of tetrabutylammoniumchloride is added. The solution is stirred at 110° C. for 2 hours. Theyellow, slightly viscous solution can be used direct for coating copperplates. The inherent viscosity of the polyester formed is measured on a0.5% by weight solution in cyclohexanone at 20° C.

EXAMPLE 16

7.3 g (0.0639 mol) of 2,5-dimethylpiperazine and 18 ml of triethylamineare dissolved in 100 ml of dry chloroform in a 750 ml sulphonation flaskand the solution is cooled to -5° C. At this temperature, a suspensionof 8 g (0.0193 mol) of N-(3-isophthaloyldicarboxylic acidchloride)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid imideand 10.78 g (0.045 mol) of sebacic acid dichloride in 100 ml ofchloroform is added dropwise. The reaction mixture is stirred for 3hours at room temperature and the slightly viscous solution isprecipitated with 1,500 ml of petroleum ether. 13 g of beige polymer areobtained.

EXAMPLE 17

This example relates to images which are produced by photocrosslinkingpolymers according to the invention and are rendered more easily visibleby staining and to the determination of the relative sensitivity of theimages thus obtained. A 400 watt mercury vapour high pressure lamp at adistance of 40 cm from the vacuum table is used for exposure. Theoriginal used is a Stauffer step wedge as described in "Photoresist,Material and Processes", W. S. De Forest, page 110 (McGraw-Hill BookCompany, New York, 1975).

Coating: The photo-crosslinkable polymer is applied to aluminium plates(about 0.3 mm) by whirler-coating at 1,000 revolutions/minute from a 5%solution in N,N-dimethylformamide.

Developing: 3 seconds in tetrahydrofuran; 30 seconds in 3% NaHCO₃.H₂ O.

Staining: The polymer which has been crosslinked image-wise cansubsequently easily be stained with a cationic dye, for example bystaining for 30 seconds in a 5% aqueous solution of the dye of theformula ##STR36##

Table III below gives the number of stained steps in the step wedge withthe corresponding exposure time.

                  TABLE III                                                       ______________________________________                                                                 Number of                                            Polymer                  stained steps                                        according to Exposure time                                                                             in the step wedge                                    ______________________________________                                        Example 1    6 minutes   9                                                                 3 minutes   7                                                                 1 minute    5                                                    Example 2    9 minutes   5                                                                 6 minutes   2                                                                 3 minutes   1                                                    Example 3    9 minutes   5                                                                 6 minutes   3                                                                 3 minutes   1                                                    Example 4    9 minutes   7                                                                 6 minutes   5                                                                 3 minutes   3                                                    ______________________________________                                    

EXAMPLE 18

This example relates to images which are produced by photocrosslinkingpolymers according to the invention on copper-coated plates. Theoriginal used is a Stauffer step wedge, and a 400 watt mercury vapourhigh pressure lamp at a distance of 40 cm from the vacuum stage is usedfor exposure. After exposure, the image is developed in a chloroformbath and the parts of the copper which are now uncovered are renderedmore easily visible by etching slightly in FeCl₃ solution.

Coating: The polymer is applied to copper-coated epoxide plates bywhirler-coating at 1,000 revolutions/minute from a 5% solution inN,N-dimethylformamide (layer thickness of the dry polymer about 1-3 nm).

Table IV below gives the number of steps of the step wedge shown on theimage with the corresponding exposure time.

                  TABLE IV                                                        ______________________________________                                                               Number of steps                                        Example    Exposure time                                                                             shown on the image                                     ______________________________________                                        7          3'          2                                                                 6'          3                                                      9          3'          5                                                                 6'          6                                                      10         12          5                                                      11         3'          4                                                                 6'          5                                                      12         6'          5                                                      14         6'          4                                                      ______________________________________                                    

Examples of the preparation of starting materials of the formula II orIII for the photocrosslinkable polymers Example (a)N-(2'-Hydroxyethyl)-3,4-dihydronaphthalene-1,2-dicarboximide

A solution of 70 g (0.35 mol) of 3,4-dihydronaphthalene-1,2-dicarboxylicacid anhydride [prepared according to Org. Syntheses, Col., Vol. 2, 194(1943)] and 23.5 g (0.385 mol) of ethanolamine in 1.7 liters of glacialacetic acid is kept under reflux for 24 hours. The glacial acetic acidis then removed by distillation, the residue is dissolved in 2 liters ofabsolute ethanol, 50 g of an ion exchanger ("Dowex 50 W" from Fluka AG)are added and the suspension is kept under reflux for 24 hours. The ionexchanger is then filtered off, the ethanol is distilled off and theresidue is recrystallised from diethyl ether/ethanol. This yields 61.8 g(73% of theory) ofN-(2'-hydroxyethyl)-3,4-dihydronaphthalene-1,2-dicarboximide; meltingpoint 120.5°-121° C.

Example (b)N-(2'-Hydroxyethyl)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylicacid imide

1. 4.5 g of ethanolamine are added at room temperature (20°-25° C.) to asolution of 15 g (0.07 mol) of6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid anhydride in 150ml of toluene. The mixture is refluxed for 2 hours and the water formedis removed continuously using a water separator. The toluene is thenremoved by distillation and the residue is recrystallised from ethanol.This yields 1.4 g (82% of theory) of yellow crystals with a meltingpoint of 115° C.

The preparation of 6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylicacid anhydride is described in paragraphs 2. 3. and 4. below:

2. Ethyl 5-phenylvalerate

250 g (1.4 mols) of 5-phenylvaleric acid are dissolved in 450 ml ofabsolute ethanol. 114 ml of concentrated sulphuric acid are added to theclear colourless solution and the reaction mixture is refluxed for 48hours. The reaction mixture, which initially is two-phase, becomesalmost homogeneous and separates into two phases again on cooling. Thecold two-phase reaction mixture is poured onto diethyl ether and about 1kg of ice. The aqueous phase is extracted with ether twice more. Theether phases are washed twice with 2 N sodium carbonate solution andtwice with NaCl solution. The combined ether phases are dried over MgSO₄and the solvent is removed on a rotary evaporator. After drying under ahigh vacuum at room temperature, 281.7 g of a colourless oil (97.5% oftheory) are obtained.

The crude product is used further (cf. paragraph 4.).

3. Diethyl 3-phenylpropyl-oxaloacetate ##STR37##

A suspension of oil-free sodium hydride in diethyl ether, prepared bydecanting and twice washing with diethyl ether 71.8 g of a sodiumhydride dispersion (55% in oil) in n-pentane under nitrogen, and adding3 liters of absolute diethyl ether are refluxed. A mixture of 281.7 g(1.36 mols) of ethyl 5-phenylvalerate and 297 g (1.36 mols+50%) ofdiethyl oxalate is added dropwise to the boiling suspension in thecourse of about 6 hours. The reaction mixture is then kept under refluxfor a total of 66 hours. The thin layer chromatogram (CHCl₃) shows, inaddition to a very small amount of starting material (R_(f) about 0.6),a main spot with a R_(f) of about 0.5. After cooling, the reactionmixture is poured onto 500 g of ice and 1.05 equivalents of HCl (=530 mlof 2 N HCl). The aqueous phase is extracted with diethyl ether, thediethyl ether phase is dried over MgSO₄ and the ether is removed invacuo. After drying in vacuo, 520 g of a reddish oil, which stillcontains oxalate, are obtained. The crude product is used furtherdirect.

4. 6,7-Dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid anhydride##STR38##

240 ml of 90% sulphuric acid are cooled to 0°-5° C. 30 g of ester C areadded dropwise at this temperature in the course of about 15-20 minutes.A dark yellow to reddish solution forms. The reaction mixture is thenallowed to thaw to room temperature and the course of the reaction isfollowed by means of thin layer chromatography. After about 3 to 4 hoursno further starting material is visible. Thin layer chromatogram (CHCl₃)starting material: R_(f) about 0.7; reaction product: R_(f) about 0.8.

The reaction mixture is poured onto 1.5 liters of ice and sufficientNaCl to saturate the resulting aqueous phase (about 500 g). Withvigorous stirring, a white, crystalline precipitate separates out. Thisis filtered off with suction, the material on the filter is subjected tostrong suction and taken up in diethyl ether and insoluble constituentsare separated off. The ether solution is dried over MgSO₄, concentratedon a rotary evaporator and dried under a high vacuum: 1st portion ofproduct D. The aqueous phase is extracted with diethyl ether and thediethyl ether phase is washed with NaCl solution and dried and the etheris removed on a rotary evaporator: 2nd portion of product D. On thebasis of the thin layer chromatogram, this portion is virtuallyidentical to the first portion. The two portions are combined andrecrystallised from isopropanol. This yields 10 g (47% of theory) ofcompound D in the form of pale yellowish crystals; melting point112°-113° C.

Example (c) N-(2'-Hydroxyethyl)-2-methyl-2H-chromene-3,4-dicarboximideand N-(2'-hydroxyethyl)-2,3-dihydro-1-benzoxepine-4,5-dicarboximide##STR39##

A solution of 48.65 g (0.2 mol) of2,3-dihydro-1-benzoxepine-4,5-dicarboxylic acid anhydride and 13.4 g(0.22 mol) of ethanolamine in 1.5 liters of glacial acetic acid isrefluxed for 2 days. The glacial acetic acid is then distilled off, theresidue is dissolved in 2 liters of absolute methanol, 70 g of an ionexchanger ("Dowex 50 W" from Fluka AG) are added and the suspension isrefluxed for 2 days. The ion exchanger is then filtered off, themethanol is removed by distillation and the residue is separated on asilica gel column (solvent system: toluene/ethyl acetate in a volumeratio of 2:1). The first fraction (R_(f) about 0.3) contains 9.3 g (18%of theory) of N-(2'-hydroxyethyl)-2-methyl-2H-chromene-3,4-dicarboximide(compound A) in the form of yellow crystals (recrystallised frommethylene chloride/n-hexane); melting point 124° C.

The second fraction (R_(f) about 0.2) contains 41.5 g (80% of theory) ofN-(2'-hydroxyethyl)-2,3-dihydro-1-benzoxepine-4,5-dicarboximide(compound B); melting point 136°-137° C. (recrystallised from CH₂ Cl₂/n-hexane).

The starting material [2,4-dihydro-1-benzoxepine-4,5-dicarboxylic acidanhydride] can be prepared as follows:

A solution of 22 g (0.15 mol) of diethyl oxalate in 100 ml of diethylether is added dropwise, at a temperature of 15° C., to a suspension of5 g (0.104 mol) of a 50% dispersion of sodium hydride in mineral oil in50 ml of diethyl ether, with stirring. The reaction mixture is thenstirred for 2 hours at room temperature. A solution of 21 g (0.10 mol)of ethyl phenoxy-butyrate [prepared according to Powell and Adams, J.Amer. Chem. Soc., 42, 652 (1920)] in 100 ml of diethyl ether is allowedto run in and the resulting mixture is then refluxed for 10 hours. Aftercooling, 1 ml of ethanol is added and the mixture is then poured onto amixture of 100 g of ice and 150 ml of water. The pH of the aqueous phaseis adjusted to 3 with 2 N hydrochloric acid. The layers are separated ina separating funnel and the aqueous phase is again extracted with 250 mlof diethyl ether. The combined ether extracts are washed with 100 ml ofwater, dried over magnesium sulphate and then evaporated under awaterpump vacuum. 30.8 g (100% of theory) of crude diethyl2-phenoxyethyl-oxaloacetate in the form of a pale reddish oil remain asthe residue.

30.8 g (0.10 mol) of crude diethyl 2-phenoxyethyloxaloacetate areallowed to run dropwise in the course of 15 minutes, at a temperature of5°-10° C., into an ice-cooled mixture of 225 ml of concentratedsulphuric acid and 25 ml of water. The reaction temperature is thenallowed to rise to 15° C. and the reaction mixture is stirred for onehour at this temperature. The reaction mixture is then poured into amixture of 1,000 g of ice and 1,500 ml of water, with stirring,whereupon 2,3-dihydro-1-benzoxepine-4,5-dicarboxylic acid anhydrideprecipitates out. This is filtered off with suction and recrystallisedfrom isopropanol. This yields 14.0 g of2,3-dihydro-1-benzoxepine-4,5-dicarboxylic acid anhydride (64.7% oftheory) with a melting point of 142°-143° C.

Example (d)N-(3'-Hydroxy-2',2'-dimethylpropyl)-3,4-dihydronaphthalene-1,2-dicarboxylicacid imide

20.0 g (0.1 mol) of 3,4-dihydronaphthalene-1,2-dicarboxylic acidanhydride and 10.3 g (0.1 mol) of 2,2-dimethyl-3-aminopropanol aredissolved in 60 ml of toluene and the solution is refluxed for 2 hours,the water formed being separated off by means of a water separator.After the reaction has ended, the reaction mixture is concentrated todryness in vacuo at 60° C. The residue is recrystallised from ethanol.This yields 25.1 g (87.9% of theory) ofN-(3'-hydroxy-2',2'-dimethylpropyl)-3,4-dihydronaphthalene-1,2-dicarboxylicacid imide.

Example (e)N-(3'-Hydroxy-2',2'-dimethylpropyl)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylicacid imide

21.4 g (0.1 mol) of 6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylicacid anhydride and 10.3 g (0.1 mol) of 2,2-dimethyl-3-aminopropanol aredissolved in 60 ml of toluene and the solution is refluxed for 1 hour,the water formed being separated off by means of a water separatordownstream of the reaction vessel. After cooling to room temperature,the crystals which have precipitated out are filtered off. This yields28.9 g (96.6% of theory) ofN-(3'-hydroxy-2',2'-dimethylpropyl)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylicacid imide.

Example (f)N-(2'-Methacryloyloxyethyl)-3,4-dihydronaphthalene-1,2-dicarboxylic acidimide

24.3 g (0.1 mol) ofN-(2'-hydroxyethyl)-3,4-dihydronaphthalene-1,2-dicarboxylic acid immide,12.9 g (0.15 mol) of methacrylic acid, 1.6 ml of concentrated sulphiricacid and 1.0 g of 2,6-di-tert.-butyl-p-cresol are dissolved in tolueneand the solution is refluxed for 2 hours, the water formed beingseparated off by means of a water separator downstream of the reactionvessel. The reaction solution is then cooled to room temperature, 5.52 g(0.075 mol) of calcium hydroxide are added and the mixture is stirredthoroughly for 5 minutes. After filtering, the filtrate is concentratedto dryness in vacuo at 60° C. This yields 28.8 g (95.7% of theory) ofN-(2'-methacryloyloxyethyl)-3,4-dihydronaphthalene-1,2-dicarboxylic acidimide.

Example (g) ##STR40##

A solution of 20 g (0.1 mol) of 3,4-dihydronaphthalene-1,2-dicarboxylicacid anhydride and 13.1 g (0.1 mol) of 6-aminocaproic acid in 130 ml ofacetic acid is refluxed for 6 hours. The reaction solution isevaporated. The yellow solid product, which has a melting point of109°-111° C., is recrystallised from 100 ml of carbon tetrachloride.

Yield: 23.9 g (76.2% of theory) melting point 108°-111° C., crystals.

Analysis: calculated: C 69.00%, H 6.11%, N 4.47%; found: C 68.78%, H6.12%, N 4.69%.

NMR spectrum (DMSOCH₆): =7.9 [1H]; 7.15 [3H]; 3.40 [2H, t]; 3.00 [2H,t]; 2.60 [2H, t]; 2.20 [2H, t]; 1.8-1.1 [6H, Mp].

Example (h) ##STR41##

2 g (0.0062 mol) of the N-(caproicacid)-3,4-dihydronaphthalene-1,2-dicarboximide obtained according toExample (g) and 0.51 ml (0.007mol) of thionyl chloride are dissolved in10 ml of methylene chloride and the solution is stirred at roomtemperature for 24 hours. It is then refluxed for 3 hours and evaporatedto dryness. This yields 2 g (94.4% of theory) of an oily product whichcrystallises after 24 hours. Melting point 65°-67° C.

Analysis: calculated: C 65.16%, H 5.47%, N 4.22%, Cl 10.69%; found: C65.34%, H 5.54%, N 4.31%, Cl 9.51%.

Example (i) ##STR42##

A solution of 60.82 g ofN-(2'-hydroxyethyl)-3,4-dihydronaphthalene-1,2-dicarboxylic acid imide,24.51 g (0.34 mol) of acrylic acid and 5 ml of chemically pure H₂ SO₄ in240 ml of toluene, with the addition of 1.2 g of Cu-II acetate, isrefluxed for 11/2 hours, the water formed (4.5 ml) being separated offby means of a water separator.

The solution, which has cooled to room temperature, is neutralised with300 ml of 8% NaHCO₃ solution. The aqueous phase is extracted with 2×400ml of toluene. The organic phase is washed with 100 ml of water, driedand evaporated.

Yield: 53.3 g=71.65%, melting point 86°-89° C.

Analysis: calculated: C 68.68%, H 5.09%, N 4.71%; found: C 68.36%, H5.1%, N 4.74%.

Example (j) ##STR43##

9.5 g (0.100 mol) of phenol are dissolved in 500 ml of anhydrous tolueneand the solution is refluxed. 55 ml of toluene are distilled off (dryingof the phenol) and the solution is cooled to room temperature. At roomtemperature, 20 g (0.05 mol) of N-(4'-isophthalic aciddichloride)-3,4-dihydronaphthalene-1,2-dicarboximide and 10.36g oftriethylamine are added and the mixture is stirred for 50 hours at roomtemperature. The thick suspension is diluted with 200 ml of toluene andfiltered with suction. The yellow filtrate is evaporated and the residueis recrystallised from 70 ml of ethylene glycol monomethyl ether.

Yield: 9 g=35% of theory, melting point 205°-208° C.

Analysis: calculated: C 74.56%, H 4.11%, N 2.72%; found: C 74.41%, H3.95%, N 2.78%.

Example (k)

16.25 g (0.077 mol) of disodium 3-aminoisophthalate, 150 ml of water,150 ml of dimethylacetamide and 16.48 g (0.077 mol) of6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid anhydride arewarmed to 100°, with stirring. The clear solution is stirred at 100° for1 hour. After cooling to 80°, 85 ml of 2 N HCl solution are addeddropwise. The yellow suspension, which has been cooled to roomtemperature, is filtered with suction and the material on the suctionfilter is washed with 100 ml of cold water and dried in vacuo at 100°for 12 hours. This yields 28 g (96.7% of theory) ofN-(3-isophthaloyldicarboxylicacid)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid imide whichhas the following elementary analysis for the empirical formula C₂₁ H₁₅NO₆ : calculated: C 66.84%, H 4.01%, N 3.71%; found: C 65.8%, H 3.97%, N3.60%.

Example (l)

5 g (0.013 mol) of N-(3-isophthaloyldicarboxylicacid)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid imide, 2drops of dimethylformamide and 26 ml of thionyl chloride are refluxedfor 30 minutes. The red solution is evaporated and the red crystallineproduct is recrystallised from 30 ml of dry toluene. This yields 2.4 g(43.7% of theory) of N-(3-isophthaloyldicarboxylic acidchloride)-6,7-dihydro-5H-benzocycloheptene-8,9-dicarboxylic acid imidewhich has a melting point of 178°-181° and the following elementaryanalysis, calculated for the empirical formula C₂₁ H₁₃ NO₄ Cl₂ :calculated: C 60.89%, H 3.17%, N 3.38%, Cl 17.12%; found: C 60.75%, H3.21%, N 3.59%, Cl 16.9%.

What is claimed is:
 1. A photo-crosslinkable polymer, which has anaverage molecular weight between 1,000 and 50,000, as measured byinherent viscosity on a 0.5% by weight solution in cyclohexanone at 20°C. and which has side imidyl groups of the formula (I) ##STR44## inwhich R and R₁ independently of one another are hydrogen, halogen, alkylhaving 1-4 C atoms or methoxy, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂ --with the oxygen atom bonded to the aromatic ring and E is hydrogen, or Ais --O-- and E is --CH₃, the proportion of imidyl groups of the formulaI being at least 5 percent, based on the number of recurring structuralelements in the polymer, said polymer being a polyester which is ahomopolycondensation product or a copolycondensation product of adicarboxylic acid or ester forming derivative thereof with a dihydroxyor diglycidyl compound, wherein said polymer comprises(a) from 5 to 100percent, based on recurring structural elements in the polymer chain, ofmolecular chain members of the formula XV ##STR45## in which Z₃ and Z₄are --O--, and G is an aliphatic radical having at least 2 C atoms or acycloaliphatic, araliphatic, carbocyclicaromatic orheterocyclic-aromatic radical, or Z₃ --G--Z₄ -- is a grouping of theformulae ##STR46## the two carbonyl groups in the formula XV beingbonded to the benzene ring in the meta- or para-position relative to oneanother, and (b) from 95 to 0 percent, based on recurring structuralelements in the polymer chain, of structural elements of the formulaXVII ##STR47## in which Z₃, Z₄ and G are as defined under formula XV, mand r are each the number 1, and G₁ is an aliphatic radical having atleast 2 C atoms or a cycloaliphatic, araliphatic, carbocyclic-aromaticor heterocyclic-aromatic radical.
 2. A polymer according to claim 1,which comprises(a) from 5 to 100 percent, based on recurring structuralelements in the polymer chain, of molecular chain members of the formulaXVa ##STR48## (b) from 95 to 0 percent, based on recurring structuralelements in the polymer chain, of molecular chain members of the formulaXVIIa ##STR49## in which formula imidyl is a radical of the formula I inwhich R and R₁ are each hydrogen, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂-- with the oxygen atom bonded to the aromatic ring and E is hydrogen,and Z₃ and Z₄ are each --O--, G is alkylene having 2-12 C atoms orarylene having 6-10 C atoms, or arylene substituted by halogen atoms orby alkyl groups having 1-4 C atoms, and G₁ is alkylene having 2-10 Catoms or 1,3- or 1,4-phenylene.
 3. A homopolymer according to claim 1which has the recurring structural element ##STR50##
 4. A polymeraccording to claim 1, which contains imidyl groups of the formula I inwhich R and R₁ are each hydrogen, A is --CH₂ --, --CH₂ CH₂ -- or --OCH₂-- with the oxygen atom bonded to the aromatic ring and E is hydrogen.5. A polymer according to claim 1, in which the proportion of imidylgroups of the formula I is 20-100 percent, based on the number ofrecurring structural elements in the polymer.